/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.mongodb;



import com.google.auto.value.AutoValue;

import com.mongodb.BasicDBObject;

import com.mongodb.MongoClient;

import com.mongodb.client.MongoCollection;

import com.mongodb.client.MongoCursor;

import com.mongodb.client.model.Projections;

import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.transforms.SerializableFunction;

import org.bson.BsonDocument;

import org.bson.Document;

import org.bson.conversions.Bson;



import javax.annotation.Nullable;

import java.util.Collections;

import java.util.List;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkArgument;



/** Builds a MongoDB FindQuery object. */

@Experimental(Experimental.Kind.SOURCE_SINK)

@AutoValue

public abstract class FindQuery

    implements SerializableFunction<MongoCollection<Document>, MongoCursor<Document>> {



  @Nullable

  abstract BsonDocument filters();



  abstract int limit();



  abstract List<String> projection();



  private static Builder builder() {

    return new AutoValue_FindQuery.Builder()

        .setLimit(0)

        .setProjection(Collections.emptyList())

        .setFilters(new BsonDocument());

  }



  abstract Builder toBuilder();



  public static FindQuery create() {

    return builder().build();

  }



  @AutoValue.Builder

  abstract static class Builder {

    abstract Builder setFilters(@Nullable BsonDocument filters);



    abstract Builder setLimit(int limit);



    abstract Builder setProjection(List<String> projection);



    abstract FindQuery build();

  }



  /** Sets the filters to find. */

  private FindQuery withFilters(BsonDocument filters) {

    return toBuilder().setFilters(filters).build();

  }



  /** Convert the Bson filters into a BsonDocument via default encoding. */

  static BsonDocument bson2BsonDocument(Bson filters) {

    return filters.toBsonDocument(BasicDBObject.class, MongoClient.getDefaultCodecRegistry());

  }



  /** Sets the filters to find. */

  public FindQuery withFilters(Bson filters) {

    return withFilters(bson2BsonDocument(filters));

  }



  /** Sets the limit of documents to find. */

  public FindQuery withLimit(int limit) {

    return toBuilder().setLimit(limit).build();

  }



  /** Sets the projection. */

  public FindQuery withProjection(List<String> projection) {

    checkArgument(projection != null, "projection can not be null");

    return toBuilder().setProjection(projection).build();

  }



  @Override

  public MongoCursor<Document> apply(MongoCollection<Document> collection) {

    return collection

        .find()

        .filter(filters())

        .limit(limit())

        .projection(Projections.include(projection()))

        .iterator();

  }

}